Where is my oil sensor on a 2000 pontiac bonneville.

If the brown stuff is oily, it could in fact be oil from the engine. If so, the engine may have a blown head gasket or other internal leak.

Loose or missing gasket on the drain plug, loose oil filter.

It is on the oil filter housing, let me verify that in the service manual. I will get back to you if it is not in that location

Hello: If your car has the 3800 V/6 engine then try this, on the passenger side of the car toward the windshield on the lower part of the engine where the oil filter is mounted you will see the oil pressure sensor with one wire attached to it. Disconnect the wire and turn the key on, if the gage stays at zero then the sensor may be bad (stuck) you may have to replace it. It takes a special socket to remove it. Auto Zone, Advance Auto Parts should have the socket and they may also carry the sensor(cheaper than GM part).

mass air flow sensor is located on the air hose that leads to the air filter if you have the part just look for the same look to make sure.

Replace oil pressure sensor. What is the code?

Its on the right side of the camshaft cover. you will need to remove the right cover to pull.

Oil sending unit bad. Replace.

The oil pressure sending unit is located behind the oil filter, Threaded into an aluminunm housing. It has wiring that plugs into the sending unit. The oil filter has to be removed and you will need a deep well socket and a 6 inch extension. Change the oil and the sending unit together.

like 3/4 or 7/8